diff --git a/Cargo.lock b/Cargo.lock
index 626d0c0..dfb2d87 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -163,6 +163,7 @@ version = "0.0.0"
 dependencies = [
  "assert_cmd",
  "clap",
+ "globset",
  "predicates",
  "serde",
  "serde_json",
@@ -254,6 +255,19 @@ dependencies = [
  "wasip3",
 ]
 
+[[package]]
+name = "globset"
+version = "0.4.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "52dfc19153a48bde0cbd630453615c8151bce3a5adfac7a0aebfbf0a1e1f57e3"
+dependencies = [
+ "aho-corasick",
+ "bstr",
+ "log",
+ "regex-automata",
+ "regex-syntax",
+]
+
 [[package]]
 name = "hashbrown"
 version = "0.15.5"
diff --git a/Cargo.toml b/Cargo.toml
index 23ae411..25cbd0c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,6 +12,7 @@ tracing-subscriber = { version = "0.3", default-features = false, features = ["f
 tracing-appender = "0.2"
 serde_yaml = "0.9"
 walkdir = "2"
+globset = "0.4"
 
 [dev-dependencies]
 tempfile = "3"
diff --git a/src/parser/ignore.rs b/src/parser/ignore.rs
new file mode 100644
index 0000000..f3d011b
--- /dev/null
+++ b/src/parser/ignore.rs
@@ -0,0 +1,112 @@
+use globset::{Glob, GlobSet, GlobSetBuilder};
+use std::fmt;
+use std::path::Path;
+
+const DEFAULT_PATTERNS: &[&str] = &[
+    "node_modules/**",
+    "target/**",
+    "dist/**",
+    ".git/**",
+    ".commandindex/**",
+    "*.min.js",
+    "*.lock",
+];
+
+#[derive(Debug)]
+pub enum IgnoreError {
+    Io(std::io::Error),
+}
+
+impl fmt::Display for IgnoreError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            IgnoreError::Io(e) => write!(f, "IO error: {e}"),
+        }
+    }
+}
+
+impl std::error::Error for IgnoreError {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        match self {
+            IgnoreError::Io(e) => Some(e),
+        }
+    }
+}
+
+impl From<std::io::Error> for IgnoreError {
+    fn from(e: std::io::Error) -> Self {
+        IgnoreError::Io(e)
+    }
+}
+
+pub struct IgnoreFilter {
+    glob_set: GlobSet,
+}
+
+impl Default for IgnoreFilter {
+    fn default() -> Self {
+        let mut builder = GlobSetBuilder::new();
+        for pattern in DEFAULT_PATTERNS {
+            if let Ok(glob) = Glob::new(pattern) {
+                builder.add(glob);
+            }
+        }
+        let glob_set = builder.build().unwrap();
+        Self { glob_set }
+    }
+}
+
+impl IgnoreFilter {
+    /// `.cmindexignore` ファイルからフィルターを構築する。
+    /// ファイルが存在しない場合はデフォルトルールを使用する。
+    pub fn from_file(path: &Path) -> Result<Self, IgnoreError> {
+        if path.exists() {
+            let content = std::fs::read_to_string(path)?;
+            Ok(Self::from_content(&content))
+        } else {
+            Ok(Self::default())
+        }
+    }
+
+    /// パターン文字列からフィルターを構築する
+    pub fn from_content(content: &str) -> Self {
+        let mut builder = GlobSetBuilder::new();
+
+        for line in content.lines() {
+            let trimmed = line.trim();
+
+            // Skip empty lines and comments
+            if trimmed.is_empty() || trimmed.starts_with('#') {
+                continue;
+            }
+
+            // Normalize directory patterns: "dir/" -> "dir/**"
+            let pattern = if trimmed.ends_with('/') {
+                format!("{trimmed}**")
+            } else {
+                trimmed.to_string()
+            };
+
+            match Glob::new(&pattern) {
+                Ok(glob) => {
+                    builder.add(glob);
+                }
+                Err(e) => {
+                    tracing::warn!("Invalid glob pattern '{}': {}", trimmed, e);
+                }
+            }
+        }
+
+        let glob_set = builder.build().unwrap_or_else(|e| {
+            tracing::warn!("Failed to build glob set: {}", e);
+            GlobSetBuilder::new().build().unwrap()
+        });
+
+        Self { glob_set }
+    }
+
+    /// パスが除外対象かどうかを判定する
+    pub fn is_ignored(&self, path: &Path) -> bool {
+        self.glob_set.is_match(path)
+    }
+}
diff --git a/src/parser/mod.rs b/src/parser/mod.rs
index b769775..02ed070 100644
--- a/src/parser/mod.rs
+++ b/src/parser/mod.rs
@@ -1,4 +1,5 @@
 pub mod frontmatter;
+pub mod ignore;
 pub mod link;
 pub mod markdown;
 
diff --git a/tests/ignore_filter.rs b/tests/ignore_filter.rs
new file mode 100644
index 0000000..df0985b
--- /dev/null
+++ b/tests/ignore_filter.rs
@@ -0,0 +1,142 @@
+use commandindex::parser::ignore::IgnoreFilter;
+use std::fs;
+use std::path::Path;
+use tempfile::TempDir;
+
+// === Default rules tests ===
+
+#[test]
+fn test_default_ignores_node_modules() {
+    let filter = IgnoreFilter::default();
+    assert!(filter.is_ignored(Path::new("node_modules/foo/bar.js")));
+}
+
+#[test]
+fn test_default_ignores_target() {
+    let filter = IgnoreFilter::default();
+    assert!(filter.is_ignored(Path::new("target/debug/build")));
+}
+
+#[test]
+fn test_default_ignores_git() {
+    let filter = IgnoreFilter::default();
+    assert!(filter.is_ignored(Path::new(".git/objects/abc")));
+}
+
+#[test]
+fn test_default_ignores_commandindex() {
+    let filter = IgnoreFilter::default();
+    assert!(filter.is_ignored(Path::new(".commandindex/tantivy/index")));
+}
+
+#[test]
+fn test_default_ignores_min_js() {
+    let filter = IgnoreFilter::default();
+    assert!(filter.is_ignored(Path::new("vendor/jquery.min.js")));
+}
+
+#[test]
+fn test_default_ignores_lock_files() {
+    let filter = IgnoreFilter::default();
+    assert!(filter.is_ignored(Path::new("Cargo.lock")));
+    assert!(filter.is_ignored(Path::new("yarn.lock")));
+}
+
+#[test]
+fn test_default_allows_normal_files() {
+    let filter = IgnoreFilter::default();
+    assert!(!filter.is_ignored(Path::new("src/main.rs")));
+    assert!(!filter.is_ignored(Path::new("docs/README.md")));
+    assert!(!filter.is_ignored(Path::new("app.js")));
+}
+
+// === Custom rules tests ===
+
+#[test]
+fn test_custom_patterns() {
+    let content = "*.log\nbuild/\nsecrets.json";
+    let filter = IgnoreFilter::from_content(content);
+
+    assert!(filter.is_ignored(Path::new("app.log")));
+    assert!(filter.is_ignored(Path::new("build/output.bin")));
+    assert!(filter.is_ignored(Path::new("secrets.json")));
+    assert!(!filter.is_ignored(Path::new("src/main.rs")));
+}
+
+#[test]
+fn test_comment_lines_ignored() {
+    let content = "# This is a comment\n*.log\n# Another comment";
+    let filter = IgnoreFilter::from_content(content);
+
+    assert!(filter.is_ignored(Path::new("debug.log")));
+    assert!(!filter.is_ignored(Path::new("src/main.rs")));
+}
+
+#[test]
+fn test_empty_lines_ignored() {
+    let content = "\n*.log\n\n*.tmp\n\n";
+    let filter = IgnoreFilter::from_content(content);
+
+    assert!(filter.is_ignored(Path::new("debug.log")));
+    assert!(filter.is_ignored(Path::new("temp.tmp")));
+}
+
+#[test]
+fn test_directory_pattern_with_trailing_slash() {
+    let content = "vendor/";
+    let filter = IgnoreFilter::from_content(content);
+
+    assert!(filter.is_ignored(Path::new("vendor/lib/foo.js")));
+    assert!(!filter.is_ignored(Path::new("src/vendor.rs")));
+}
+
+#[test]
+fn test_invalid_pattern_skipped() {
+    let content = "*.log\n[invalid\n*.tmp";
+    let filter = IgnoreFilter::from_content(content);
+
+    assert!(filter.is_ignored(Path::new("debug.log")));
+    assert!(filter.is_ignored(Path::new("temp.tmp")));
+    // Invalid pattern should be skipped, not cause an error
+}
+
+#[test]
+fn test_empty_content() {
+    let content = "";
+    let filter = IgnoreFilter::from_content(content);
+    assert!(!filter.is_ignored(Path::new("anything.rs")));
+}
+
+// === File-based tests ===
+
+#[test]
+fn test_from_file_exists() {
+    let tmp = TempDir::new().unwrap();
+    let ignore_path = tmp.path().join(".cmindexignore");
+    fs::write(&ignore_path, "*.log\nbuild/").unwrap();
+
+    let filter = IgnoreFilter::from_file(&ignore_path).unwrap();
+    assert!(filter.is_ignored(Path::new("app.log")));
+    assert!(filter.is_ignored(Path::new("build/output.bin")));
+    assert!(!filter.is_ignored(Path::new("src/main.rs")));
+}
+
+#[test]
+fn test_from_file_not_exists_uses_defaults() {
+    let tmp = TempDir::new().unwrap();
+    let ignore_path = tmp.path().join(".cmindexignore");
+    // File does not exist
+
+    let filter = IgnoreFilter::from_file(&ignore_path).unwrap();
+    // Should use default rules
+    assert!(filter.is_ignored(Path::new("node_modules/foo.js")));
+    assert!(filter.is_ignored(Path::new("target/debug/build")));
+    assert!(!filter.is_ignored(Path::new("src/main.rs")));
+}
+
+#[test]
+fn test_only_comments_and_blanks() {
+    let content = "# comment\n\n# another comment\n  \n";
+    let filter = IgnoreFilter::from_content(content);
+    assert!(!filter.is_ignored(Path::new("anything.txt")));
+}